Systems and methods for supplying a constant power to a therapy delivery target

Abstract

The present disclosure relates to a system including processing circuitry configured to receive information relating to a therapy program of an implantable medical device. The processing circuitry may be further configured to measure a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time; determine a measured impedance at the therapy delivery target at the subsequent time; determine a second power measurement supplied to the therapy delivery target at the subsequent time; and compare the first power measurement to the second power measurement. The processing circuitry may adjust at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

Description

Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 SYSTEMS AND METHODS FOR SUPPLYING A CONSTANT POWER TO A THERAPY DELIVERY TARGETCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No.63 / 779,649, entitled “SYSTEMS AND METHODS FOR SUPPLYING A CONSTANT POWER TO A THERAPY DELIVERY TARGET”, filed on March 28, 2025, the disclosure of which is incorporated by reference herein in its entirety.FIELD

[0002] The disclosure relates to implantable medical devices, and, more specifically, systems and methods for supplying a constant power to a therapy delivery target.BACKGROUND

[0003] Medical devices may be external or implanted and may be used to monitor patient signals such as cardiac activity, biological impedance and to deliver electrical stimulation therapy to patients via various tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson’s disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis and other conditions. In some examples, medical devices may include a rechargeable or primary cell electrical power source, or may be powered directly by transmitting energy through tissue.SUMMARY

[0004] In certain embodiments, the present disclosure includes a system having processing circuitry configured to: receive information relating to a therapy program of an implantable medical device including a first power measurement supplied to a therapy delivery target at an initial time; measure a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time; determine, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time; determine, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; compare the first power measurement to the second power measurement; and adjust atAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0005] In certain embodiments, a method for supplying a constant power to a therapy delivery target includes: receiving information relating to a therapy program of an implantable medical device comprising a first power measurement supplied to the therapy delivery target at an initial time: measuring a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time; determining, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time; determining, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; comparing the first power measurement to the second power measurement; and adjusting at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0006] In certain embodiments, a method for training a machine learning algorithm to supply a constant power to a therapy delivery target includes providing a labeled dataset comprising information relating to one or more therapy programs, the one or more therapy programs including: a first power measurement supplied to the therapy delivery target at an initial time; a voltage supplied by a power source at a subsequent time; a current supplied to the therapy delivery target at the subsequent time; and a labeled impedance at the therapy delivery target at the subsequent time; generating a non-linear regression model for determining a measured impedance at the therapy delivery target at the subsequent time; determining, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; evaluating the machine learning algorithm’s performance by comparing the first power measurement to the second power measurement; and adjusting the non-linear regression model when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0007] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, andAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. l is a conceptual diagram illustrating an example medical device system including an implantable medical device, which may be a leadless neurostimulation device, implanted near a tibial nerve in a leg of a patient, in accordance with one or more embodiments of the present disclosure.

[0009] FIG. 2 is a block diagram illustrating example components of the implantable medical device of FIG. 1, in accordance with one or more embodiments of the present disclosure.

[0010] FIG. 3 is a block diagram of an example external charging device, in accordance with one or more embodiments of the present disclosure.

[0011] FIG. 4 is a block diagram of an example programmer of FIG. 1, in accordance with one or more embodiments of the present disclosure.

[0012] FIG. 5 is a block diagram illustrating example system inputs that are received by the programmer of FIGS. 1 and 4, in accordance with one or more embodiments of the present disclosure.

[0013] FIG. 6 is a block diagram illustrating example system outputs generated by the programmer of FIGS. 1 and 5, in accordance with one or more embodiments of the present disclosure.

[0014] FIG. 7 is a scatter plot diagram illustrating a stack setting ( / .< ., how many capacitors are required to support a given voltage as stimulation increases) increasing as current amplitude increases, in accordance with one or more embodiments of the present disclosure.

[0015] FIG. 8 is a scatter plot diagram illustrating an increase in the average current that drains from a battery as the total impedance increases, in accordance with one or more embodiments of the present disclosure.

[0016] FIG. 9 is a three-dimensional scatter plot diagram illustrating a relationship between the average current, current amplitude, and total impedance, in accordance with one or more embodiments of the present disclosure.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0017] FIG. 10 is line plot diagram illustrating changes in impedance over time after implanting an IMD, in accordance with one or more embodiments of the present disclosure.

[0018] FIG. 11 is a line plot diagram illustrating changes in impedance over time including a variability gauge (e.g., a standard deviation plot diagram), in accordance with one or more embodiments of the present disclosure.

[0019] FIG. 12 includes data from a plurality of patients illustrating changes in impedance over time after implanting an IMD, in accordance with one or more embodiments of the present disclosure.

[0020] FIG. 13 is a line plot diagram of final amplitude over time for a plurality of patients after IMD implantation, in accordance with one or more embodiments of the present disclosure.

[0021] FIG. 14 is a line plot diagram of stimulation power over time for a plurality of patients after IMD implantation, in accordance with one or more embodiments of the present disclosure.

[0022] FIG. 15 is a scatter plot diagram illustrating changes in stimulation power over time including a variability gauge (e.g., a standard deviation plot diagram), in accordance with one or more embodiments of the present disclosure.

[0023] FIG. 16 is a method flow diagram of a method for supplying a constant power to a therapy delivery target, in accordance with one or more embodiments of the present disclosure.

[0024] FIG. 17 is a method flow diagram of a method for training a machine learning algorithm to supply a constant power to a therapy delivery target, in accordance with one or more embodiments of the present disclosure.DETAILED DESCRIPTION

[0025] This disclosure describes devices, systems, and techniques for supplying a constant power to a therapy delivery target using an implantable medical device (IMD). Maintaining a constant power output in implantable medical devices is desirable to ensure their reliable performance, particularly as the impedance of the surrounding tissue changes during the healing process. When an implant is first placed, the wound environment andAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 tissue conductivity can vary significantly, leading to fluctuations in impedance. As the wound heals and scar tissue forms, impedance typically increases, which can impact the device's ability to deliver consistent therapeutic or diagnostic outputs. If power delivery is not properly regulated, the device may underperform or overcompensate, potentially causing harm to a patient or reducing the IMD’s efficacy. By employing advanced power management systems that adapt to changing impedance, implantable devices can maintain stable operation, optimize energy efficiency, and enhance patient safety and outcomes over the long term.

[0026] In general, this disclosure is directed to devices, systems, and techniques for supplying a constant power to a therapy delivery target using an implantable medical device (IMD). This disclosure is also directed to devices, systems, and techniques for supplying a constant power by determining a measured impedance, determining a measured power supplied to the implant based on the measured impedance, and adjusting one or more parameters when a difference between an initial power supplied by the IMD and the measured power is not within an acceptable range. In certain embodiments, one or more steps provided herein may be performed using a machine learning algorithm.

[0027] In one or more examples described herein, an IMD includes a power source (e.g., a battery), and is configured to deliver therapy according to one or more therapy schedules. In some examples, one or more components of the system includes suitable hardware and / or software configurations for determining information about the power source (e.g., components for measuring or estimating a supplied voltage and / or charge consumption of the power source). Information of the power source may be used to determine a measured impedance at one or more times during or after an IMD is implanted into a patient according to the techniques described herein. Furthermore, information from the power source may be used to determine a power supplied to the IMD during or after implantation of the IMD, and one or more parameters can be adjusted to change the power supplied to the IMD according to the techniques described herein.

[0028] In examples described herein, the system uses information from therapy programming (e.g., therapy parameters and / or therapy schedules), as well as IMD information, including from the power source of the IMD, to supply power to the IMD based on the therapy schedule. When monitoring the power supplied to a patient, it is desirable to consider the therapy programming because the impedance and current mayAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 fluctuate over time, particularly as wound healing occurs around the IMD. During the healing process, changes in the tissue environment, such as swelling, scarring, or tissue regeneration, can affect the electrical impedance at the site of the implant. These variations can influence the amount of electrical current required to maintain the desired therapeutic effect, which in turn affects the power drawn from the battery or power source of the IMD. As the healing progresses, adjustments to the therapy programming might be needed to ensure consistent power delivery to prevent either under stimulation or overstimulation. By considering these factors, healthcare providers can optimize performance of the IMD, ensuring that the power supplied remains safe, effective, and aligned with the patient's evolving condition.

[0029] In some examples, the system is configured to adjust a measured current or voltage based on a determined power being supplied by a battery of an IMD to ensure a consistent power is being supplied as impedance changes over time. This may occur when, by non-limiting example, a first power measurement (e.g., a power supplied at a time of implantation) and a second power measurement (e.g., a power measured at some time after implantation) is not within an acceptable range.

[0030] In some examples, one or more parameters discussed herein may be generated for output to a user, e.g., on a user interface. For example, a user interface of a programmer, or another device, may be configured to display one or more of information relating to a therapy program, a measured voltage supplied to a power source, a measured impedance, a first power measurement (e.g., a power measurement supplied by the power source of the IMD at the time of implantation), a second power measurement (e.g., a power measurement supplied by the power source of the IMD at a time after implantation), a comparison between the first power measurement and the second power measurement, and one or more recommendations to adjust a current or voltage of the battery of the IMD when a difference between the first power measurement and the second power measurement is not within an acceptable range. In other examples, the user may be allowed to adjust their preferred therapy within clinician prescribed limits. Additionally, patients may be able to record quantitative and qualitative info about the sensation of the stimulation and enter this into the user interface.

[0031] Furthermore, in some examples, the system described herein is configured to supply a voltage to one or more devices while only measuring current flow through theAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 one or more devices. Further yet, as described herein, an impedance may be estimated rather than measured (e.g., the current may be the only parameter measured within a system where the impedance is estimated). In examples, changes in impedance can be used to determine a target power for the IMD, and the IMD may be programmed with an updated current or voltage value based on current impedance. In examples, determining a target power may be computed by the IMD or an external device.

[0032] Although this disclosure is discussed primarily in terms of intervals of time (e.g. interval values), which may represent a length or period of time (e.g., 1 week), it should be understood that frequencies (e.g., frequency values), which represent a recurring event (e.g., every day, every week, once per week, weekly, etc.) are contemplated to be used in addition to or instead of intervals, such as in any examples discussed herein where a system is configured to determine, use, and / or display such values in the context of supplying a constant power to an IMD.

[0033] Additionally, although the devices, systems, and techniques described herein are described primarily in the context of providing constant power from an IMD such as a tibial nerve stimulator configured to provide tibial nerve stimulation, the techniques described herein may be applicable to other devices configured for other types of therapy. For example, the techniques of this disclosure may be applicable for other types of devices configured for invasive or noninvasive neuromodulation for pain relief, muscle activation, and / or other therapeutic benefits such as, but not limited to, deep brain stimulation (DBS), spinal cord stimulation (SCS), sacral nerve stimulation (SNS), cardiac stimulation, pacing, defibrillation, or other cardiac therapy, peripheral nerve stimulation or therapy, drug delivery (e.g., via a drug pump), circulatory support (e.g., mechanical circulatory support), or any other device (e.g., medical device) that includes a power source. Additionally, the techniques of this disclosure are not limited to rechargeable power sources, but are also applicable to other types of power sources (e.g., non-rechargeable power sources, primary cell, etc.), such as in instances a power source needs to be replaced or otherwise will cause a device to not operate as intended.

[0034] FIG. l is a conceptual diagram illustrating an example system that includes an implantable medical device and an external charging device that charges a rechargeable power source. FIG. 1 includes a system 100 including an implantable medical device (IMD) 10, an external computing device 108, a programmer 104 (which may be a patientAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 programmer or a clinician programmer), and a server 112. In some examples, the computing device 108 and the programmer 104 can be included within a single device (e.g., an implantable neurostimulator or Bluetooth low-energy implantable neurostimulator). In other examples, the techniques of this disclosure may be implemented in other non-rechargeable powered devices (e.g., using a non-rechargeable battery), for example, an implantable drug pump.

[0035] External computing device 108 includes one or more charging coils, such as external primary coil 26 or internal primary coil 28. External computing device 108 may be used to program or adjust settings of IMD 10 and may also recharge an electrical energy storage device, such as a battery, of IMD 10. External computing device 108 may also communicate with server 112. In other examples, an external device (e.g., programmer 104) separate from external computing device 108 may communicate with IMD 10 to adjust therapy and / or sensing parameters, download recorded data, or perform other functions.

[0036] Server 112 may be one or more servers in a local network or in a cloud computing environment. Server 112 may be configured to communicate with programmer 104, external computing device 108 and / or IMD 10 via wireless communication through a network access point (not shown in FIG. 1) and may be co-located with external computing device 108 and / or programmer 104, or may be located elsewhere, such as in a cloud computing data center.

[0037] The example of FIG. 1 is a side view of a patient’s leg showing a leadless neurostimulation IMD 10 near the ankle adjacent to a tibial nerve 102. IMD 10 can be implanted through the patient’s skin and cutaneous fat layer via a small incision 101 (e.g., about one to three centimeters (cm)) above the tibial nerve on a medial aspect of the patient’s ankle. While incision 101 is shown approximately horizontal to the length of the tibial nerve, other incisions or implantation techniques could be used according to physician preference. The example of FIG. 1 describes a neurostimulation implantable medical device for tibial nerve stimulation. In other examples, the techniques of this disclosure may apply to other devices, such as implantable neurostimulation system for use in spinal cord stimulation therapy and deep brain stimulation, as well as to other types of medical devices without limitation.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0038] IMD 10 may be positioned adjacent to the region defined by flexor digitorum longus and soleus in which tibial nerve 102 is contained and implanted adjacent and proximal to a fascia layer. One or more electrodes of IMD 10 may face toward tibial nerve 102. Though not shown in FIG. 1, IMD 10 may also connect to one or more leads comprising one or more electrodes (not shown in FIG. 1).

[0039] IMD 10 may be constructed of any polymer, metal, or composite material sufficient to house the components of IMD 10. In some examples, IMD 10 is constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material such as silicone or polyurethane, and surgically implanted at a site in patient near the tibial nerve. In other examples, IMD 10 is implanted near the pelvis, abdomen, or buttocks. The housing of IMD 10 may be configured to provide a hermetic seal for components, such as a rechargeable power source. In addition, the housing of IMD 10 may be selected of a material that facilitates receiving energy to charge the rechargeable power source.

[0040] Optional testing of neurostimulation IMD 10 may be performed to determine if IMD 10 has been properly positioned in proximity to tibial nerve 102 to elicit a desired response from an applied electrical stimulation. In an example, IMD 10 is controlled by programmer 104 or external computing device 108 to deliver test stimulation, and one or more indicative responses are monitored, such as toe flexion from simulation of the tibial motor neurons controlling the flexor hallucis brevis or flexor digitorum brevis, or a tingling sensation in the heel or sole of the foot excluding the medial arch. If such testing does not elicit appropriate motor or sensory responses, a clinician or other user may reposition IMD 10 and retest.

[0041] Once the clinician or other user has determined IMD 10 is properly positioned to provide an appropriate patient response to delivered stimulation therapy, the housing of device can be secured in place as needed. Securing IMD 10 may be optional as the natural shape of the region in which IMD 10 is implanted, and the shape of IMD 10 itself may have good compatibility with the surrounding tissue thus preventing IMD 10 from shifting or rolling after implantation. In some examples, leadless neurostimulation IMD 10 may further include one or more suture points to help secure IMD 10 to fascia or other parts of the patient. In some examples, a suture anchor may be included, such as at the distal end of the housing of IMD 10.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0042] During operation, an electrical stimulation signal may be transmitted between one or more electrodes through the fascia layer. The electrical signal may be used to stimulate tibial nerve 102 which may be useful in the treatment of overactive bladder (OAB) symptoms of urinary urgency, urinary frequency and / or urge incontinence, fecal incontinence, pain, or other symptoms.

[0043] In some examples, disease, age, and injury may impair physiological functions of a patient. In one example, bladder dysfunction, such as overactive bladder, urgency, or urinary incontinence, is a problem that may afflict people of all ages, genders, and races. Various muscles, nerves, organs, and conduits within the pelvic floor cooperate to collect, store and release urine. A variety of disorders may compromise urinary tract performance, and contribute to an overactive bladder, urgency, or urinary incontinence that interferes with normal physiological function. System 100 may help relieve some symptoms of some disorders.

[0044] Urinary incontinence may include urge incontinence and stress incontinence. In some examples, urge incontinence may be caused by disorders of peripheral or central nervous systems that control bladder micturition reflexes. Some patients may also suffer from nerve disorders that prevent proper triggering and operation of the bladder, sphincter muscles or nerve disorders that lead to overactive bladder activities or urge incontinence. In some cases, urinary incontinence may be attributed to improper sphincter function, either in the internal urinary sphincter or external urinary sphincter.

[0045] One type of therapy for treating bladder dysfunction includes delivery of electrical stimulation to a target tissue site within a patient to cause a therapeutic effect during delivery of the electrical stimulation. For example, delivery of electrical stimulation from IMD 10 to a target therapy site, e.g., a tissue site that delivers stimulation to modulate activity of a tibial nerve, spinal nerve (e.g., a sacral nerve), a pudendal nerve, dorsal genital nerve, an inferior rectal nerve, a perineal nerve, or branches of any of the aforementioned nerves, may provide a therapeutic effect for bladder dysfunction, such as a desired reduction in frequency of bladder contractions. In some cases, electrical stimulation of the tibial nerve may modulate afferent nerve activities to restore urinary function.

[0046] Bladder dysfunction generally refers to a condition of improper functioning of the bladder or urinary tract, and may include, for example, an overactive bladder, urgency,Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 or urinary incontinence. Overactive bladder (OAB) is a patient condition that may include symptoms, such as urgency, with or without urinary incontinence. Urgency is a sudden, compelling urge to urinate, and may often, though not always, be associated with urinary incontinence. Urinary incontinence refers to a condition of involuntary loss of urine, and may include urge incontinence, stress incontinence, or both stress and urge incontinence, which may be referred to as mixed urinary incontinence. As used in this disclosure, the term “urinary incontinence” includes disorders in which urination occurs when not desired, such as stress or urge incontinence. Other bladder dysfunctions may include disorders such as non-obstructive urinary retention.

[0047] In some examples, the techniques described in this disclosure are directed to delivery of neurostimulation therapy in a non-continuous manner which may include on-cycles and off-cycles. For example, an IMD may deliver neurostimulation therapy for a specified period of time followed by a specified period of time when the IMD does not deliver neurostimulation (e.g., withholds delivery of neurostimulation). A period during which stimulation is delivered (an on-cycle) may include on and off periods (e.g., a duty cycle or bursts of pulses) with short inter-pulse durations of time when pulses are not delivered. In some examples, IMD 10 may switch between different operational modes that have different power consumptions for delivery of stimulation and non-delivery of stimulation in order to conserve power when stimulation is not to be delivered. In some examples, a continuous off period may be comparatively long, such as several days or even several weeks at a time.

[0048] The power source of IMD 10 may include one or more capacitors, batteries, or other components (e.g., chemical or electrical energy storage devices). Example batteries may include lithium-based batteries, nickel metal-hydride batteries, or other materials. The rechargeable power source may be replenished, refilled, or otherwise capable of increasing the amount of energy stored after energy has been depleted. IMD 10 may include a secondary coil 16, wherein the energy received from secondary coil 16 may be conditioned and / or transformed by a charging circuit. The charging circuit may then send an electrical signal used to charge the rechargeable power source when the power source is fully depleted or only partially depleted.

[0049] External computing device 108 may be used to recharge the rechargeable power source within IMD 10 implanted in the patient. External computing device 108 mayAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 be a hand-held device, a portable device, or a stationary charging system. External computing device 108 may also be referred to as a charging device 108 in this disclosure. External computing device 108 may include components necessary to charge IMD 10 through tissue of the patient. External computing device 108 may include an internal primary coil 28 and external primary coil 26. In other examples, external computing device may only include internal primary coil 28 and omit the use of external primary coil 26, or only include external primary coil 26 and omit the use of internal primary coil 28. External computing device 108 may include a housing to enclose operational components such as a processor, memory, user interface, telemetry module, power source, and charging circuit configured to transmit energy to secondary coil 16 via external primary coil 26 and / or internal primary coil 28. Although a user may control the recharging process with a user interface of external computing device 108, external computing device 108 may alternatively be controlled by another device, e.g., programmer 104, a computing device of server 112 such as a tablet computer, laptop, or other similar computing device. The second external computing device of server 112 may include a computing device with a touch-screen user interface. In other examples, external computing device 108 may be integrated with an external programmer, such as patient programmer 104, which may be carried by the patient.

[0050] In certain embodiments where the power source is rechargeable, external computing device 108 and IMD 10 may utilize any wireless power transfer techniques that are capable of recharging the power source of IMD 10 when IMD 10 is implanted within the patient. In some examples, system 100 may utilize inductive coupling between internal primary coil 28 and / or external primary coil 26 of external computing device 108 and secondary coils (e.g., secondary coil 16) of IMD 10. In inductive coupling, internal primary coil 28 is placed near implanted IMD 10 such that internal primary coil 28 is aligned with secondary coil 16 of IMD 10. External computing device 108 may then generate an electrical current in internal primary coil 28 based on a selected power level for charging the rechargeable power source of IMD 10. When either internal primary coil 28 or external primary coil 26 are aligned with secondary coil 16, the electrical current in either internal primary coil 28 or external primary coil 26 may magnetically induce an electrical current in secondary coil 16 within IMD 10. Since secondary coil 16 is associated with and electrically coupled to the rechargeable power source, the inducedAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 electrical current may be used to increase the voltage, or charge level, of the rechargeable power source. Although inductive coupling is generally described herein, any type of wireless energy transfer may be used to transfer energy between external computing device 108 and IMD 10.

[0051] External primary coil 26 and / or internal primary coil 28 may include a wound wire (e.g., a coil) (not shown in FIG. 1). The coil may be constructed of a wire wound in an in-plane spiral (e.g., a disk-shaped coil). In some examples, this single or even multilayers spiral of wire may be considered a flexible coil capable of deforming to conform with a non-planar skin surface. The coil may include wires that electrically couple the flexible coil to a power source and a charging module configured to generate an electrical current within the coil. Internal primary coil 28 may be external of the housing of external computing device 108 such that internal primary coil 28 can be placed on the skin of the patient proximal to IMD 10. In some examples, internal primary coil 28 may be disposed on the outside of the housing or even within housing.

[0052] Either external primary coil 26 and / or internal primary coil 28 of system 100 may include a heat sink device (not shown in FIG. 1). In the example of system 100, external computing device 108 is the power transmitting unit and IMD 10 is the power receiving unit. IMD 10 may be in a flipped or non-flipped position.

[0053] As noted above, external computing device 108 may also be referred to as charging device 108. As discussed further in connection with FIG. 3, charging device 108 may include a user interface to receive control inputs from a user, such as the patient, medical professional, or other caregiver. The user interface of charging device 108 may also provide information to a user. For example, charging device 108 may include a control configured to receive user input (not shown in FIG. 1) as well as a set of indicator lights. In some examples the indicator lights may be configured to illuminate the control. The indicator lights may also be configured to output information regarding an operational state of external computing device 108, such as a communication status and wireless power transfer status.

[0054] As discussed further in connection with FIG. 3, charging device 108 includes processing circuitry configured to perform one or more processes related to charging device 108. In some examples, the processing circuitry determines whether IMD 10 and charging device 108 have established a communication link e.g., via communicationAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 circuitry. In response to the processing circuitry determining that charging device 108 and IMD 10 have not established a communication link, the processing circuitry may cause a notification to be generated. Charging device 108 may still wirelessly transfer power to IMD 10, but the notification may signify that charging device 108 is operating in open loop charging mode.

[0055] Processing circuitry of charging device 108 may further determine whether IMD 10 is receiving wireless power. In response to determining that IMD 10 has good power coupling, such as receiving an amount of wireless power above a power threshold, the processing circuitry may cause a notification to be generated.

[0056] Processing circuitry of system 100, e.g., processing circuitry of charging device 108, processing circuitry of server 112, and / or processing circuitry of IMD 10, may determine (e.g., calculate, receive, lookup, etc.) any of the values described herein.

[0057] In certain embodiments, the processing circuitry of system 100 may perform one or more methods described herein, including, by non-limiting example, a method for supplying a constant power to a therapy delivery target.

[0058] FIG. 2 is a block diagram illustrating example components of the medical device of FIG. 1. Implantable medical device (IMD) 210 is an example of IMD 10 described above in relation to FIG. 1. In the example illustrated in FIG. 2, IMD housing 19 of IMD 210 encloses temperature sensor 39, secondary coil 16, processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, memory 32, telemetry circuitry 36, power source 18, switch 33, coulomb counter 35, state control circuitry 31, timer 41, and, in some examples, one or more sensors 37, such as an accelerometer. In other examples, IMD 210 may include a greater or a fewer number of components, e.g., in some examples, IMD 210 may not include temperature sensor 39 or sensors 37. In general, IMD 210 may comprise any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the various techniques described herein attributed to IMD 210 and processing circuitry 30, and any equivalents thereof.

[0059] Processing circuitry 30 of IMD 210 may include one or more processors, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. IMD 210 may include a memory 32, such as random-access memory (RAM),Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, comprising executable instructions for causing the processing circuitry 30 to perform the actions attributed to this circuitry. Moreover, although processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 are described as separate modules, in some examples, some combination of processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 are functionally integrated. In some examples, processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, and temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units. In this disclosure, therapy generation and sensing circuitry 34 may be referred to as therapy generation circuitry 34, for simplicity.

[0060] Memory 32 may store therapy programs or other instructions that specify therapy parameter values for the therapy provided by therapy generation circuitry 34 and IMD 210. In some examples, memory 32 stores one or more therapy schedules and / or data relating to the transition between therapy schedules. In some examples, memory 32 may also store temperature data from temperature sensor 39, instructions for supplying a constant power from the power source 18, thresholds, instructions for communication between IMD 210 and an external computing device, or any other instructions required to perform tasks attributed to IMD 210. Memory 32 may be configured to store instructions for communication with and / or controlling one or more temperature sensors of temperature sensor 39. In various examples, memory 32 stores information related to determining the temperature of housing 19 and / or exterior surface(s) of housing 19 of IMD 210 based on temperatures sensed by one or more temperature sensors, such as temperature sensor 39, located within IMD 210.

[0061] In some examples, memory 32 stores programming settings such as electrical stimulation therapy output magnitude, pulse width, as well as other therapy parameters for one or more therapy programs and / or therapy schedules. Memory 32 may determineAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 whether a sensed bioelectrical signal is valid, such as an evoked compound action potential (ECAP), local field potential (LFP) sensing, adaptive stimulation based on measurements received from an accelerometer, or other signal in response to an output electrical stimulation therapy event. Memory 32 may store programming instructions that when executed by processing circuitry 30 cause processing circuitry 30 to cause therapy generation circuitry 34 to deliver electrical stimulation therapy to a target nerve of a patient.

[0062] In some examples, memory 32 stores data related to power source 18. In some examples, memory 32 stores data of one or more instances of therapy delivery, a status of power source 18 (e.g., an estimated level of charge remaining or measured level of charge remaining), predicted future use, a power supplied to a patient at a time of implantation or at a time after implantation, measurements of voltage and / or current supplied to the IMD, and / or drain of power source 18.

[0063] Therapy generation and sensing circuitry 34 may generate and deliver electrical stimulation under the control of processing circuitry 30. In some examples, processing circuitry 30 controls therapy generation circuitry 34 by accessing memory 32 to selectively access and load at least one of the stimulation programs to therapy generation circuitry 34. For example, in operation, processing circuitry 30 may access memory 32 to load one of the stimulation programs to therapy generation circuitry 34. In such examples, relevant stimulation parameters may include a voltage amplitude, a current amplitude, a pulse rate, a pulse width, a duty cycle, or the combination of electrodes 17A, 17B, 17C, and 17D (collectively “electrodes 17”) that therapy generation circuitry 34 may use to deliver the electrical stimulation signal as well as sense biological signals. In other examples, IMD 210 may have more or fewer electrodes than the four shown in the example of FIG. 2. In some examples, electrodes 17 may be part of or attached to a housing of IMD 210, e.g., a leadless electrode. In other examples, one or more of electrodes 17 may be part of a lead implanted in or attached to a patient to sense biological signals and / or deliver electrical stimulation, as described above in relation to FIG. 1.

[0064] In some examples, one or more electrodes 17 connected to therapy generation circuitry 34 may connect to one or more sensing electrodes, e.g., attached to housing of IMD 210. In some examples, electrodes 17 may be configured to detect the evoked motorAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 response caused by the electrical stimulation therapy event, or other bioelectrical signals such as ECAPs, impedance, or other signals as appropriate.

[0065] In certain embodiments, the IMD 210 also includes components to receive power to a power source 18 when power source 18 has been at least partially depleted. As shown in FIG. 2, IMD 210 includes secondary coil 16 and recharge circuitry 38 coupled to power source 18. Recharge circuitry 38 may be configured to charge power source 18 with the selected power level determined by either processing circuitry 30 or an external charging device, such as external computing device 108 described above in relation to FIG. 1. Recharge circuitry 38 may include any of a variety of charging and / or control circuitry configured to process or convert current induced in secondary coil 16 into charging current to charge power source 18.

[0066] Secondary coil 16 may include a coil of wire or other device capable of inductive coupling with a primary coil disposed externally to a patient. Although secondary coil 16 is illustrated as a simple loop of in FIG. 2, secondary coil 16 may include multiple turns of conductive wire. Secondary coil 16 may include a winding of wire configured such that an electrical current can be induced within secondary coil 16 from a magnetic field. The induced electrical current may then be used to recharge power source 18.

[0067] Recharge circuitry 38 may include one or more circuits that process, filter, convert and / or transform the electrical signal induced in the secondary coil to an electrical signal capable of recharging power source 18. For example, in alternating current induction, recharge circuitry 38 may include a half-wave rectifier circuit and / or a fullwave rectifier circuit configured to convert alternating current from the induction to a direct current for power source 18. The full-wave rectifier circuit may be more efficient at converting the induced energy for power source 18. However, a half-wave rectifier circuit may be used to store energy in power source 18 at a slower rate. In some examples, recharge circuitry 38 may include both a full-wave rectifier circuit and a half-wave rectifier circuit such that recharge circuitry 38 may switch between each circuit to control the charging rate of power source 18 and temperature of IMD 210.

[0068] Power source 18 may include one or more capacitors, batteries, and / or other energy storage devices. Power source 18 may deliver operating power to the components of IMD 210. In some examples, power source 18 may include a power generation circuitAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 to produce the operating power. Power source 18 may be configured to operate through many discharge and recharge cycles. Power source 18 may also be configured to provide operational power to IMD 210 during the recharge process. In some examples, power source 18 may be constructed with materials to reduce the amount of heat generated during charging. In other examples, IMD 210 may be constructed of materials and / or using structures that may help dissipate generated heat at power source 18, recharge circuitry 38, and / or secondary coil 16 over a larger surface area of the housing of IMD 210. In some examples, power source 18 includes a non-rechargeable power source.

[0069] Although power source 18, recharge circuitry 38, and secondary coil 16 are shown as contained within the housing of IMD 210, in other examples, at least one of these components may be disposed outside of the housing. For example, in some implementations, secondary coil 16 may be disposed outside of the housing of IMD 210 to facilitate better coupling between secondary coil 16 and the primary coil of external charging device. In other examples, power source 18 may be a primary power cell and IMD 210 may not include recharge circuitry 38 and secondary coil 16.

[0070] Processing circuitry 30 may also control the exchange of information with an external computing device using telemetry circuitry 36. Telemetry circuitry 36 may be configured for wireless communication using radio frequency (RF) protocols, such as Bluetooth, including Bluetooth low energy (BLE), or similar RF protocols, as well as inductive communication protocols. Telemetry circuitry 36 may include one or more antennas configured to communicate with an external charging device (e.g., external computing device 108 of FIG. 1). Processing circuitry 30 may transmit operational information and receive therapy programs or therapy parameter adjustments via telemetry circuitry 36. Also, in some examples, IMD 210 may communicate with other implanted devices, such as stimulators, control devices, or sensors, via telemetry circuitry 36. In addition, telemetry circuitry 36 may be configured to control the exchange of information related to sensed and / or determined temperature data, for example temperatures sensed by and / or determined from temperatures sensed using temperature sensor 39. In some examples, telemetry circuitry 36 may communicate using inductive communication, and in other examples, telemetry circuitry 36 may communicate using RF frequencies separate from the frequencies used for inductive charging.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0071] In some examples, processing circuitry 30 may transmit, via control of telemetry circuitry 36, additional information to external charging device related to the operation of power source 18. For example, processing circuitry 30 may control telemetry circuitry 36 to transmit indications that power source 18 is completely charged, power source 18 is fully discharged, the amount of charging current output by recharge circuitry 38 e.g., to power source 18, or any other charge status of power source 18. In some examples, processing circuitry 30 may use telemetry circuitry 36 to transmit instructions to external charging device, including instructions regarding further control of the charging session, for example instructions to lower the power level or to terminate the charging session, based on the determined temperature of IMD housing 19.

[0072] Processing circuitry 30 may also transmit information to external charging device that indicates any problems or errors with power source 18 that may prevent power source 18 from providing operational power to the components of IMD 210. In various examples, processing circuitry 30 may receive, through telemetry circuitry 36, instructions for algorithms, including formulas and / or values for constants to be used in the formulas, that may be used to determine the temperature of the housing 19 and / or exterior surface(s) of housing 19 of IMD 210 based on temperatures sensed by temperature sensor 39 located within IMD 210 during and after a recharging session performed on power source 18.

[0073] IMD 210 also includes components for determining a status of power source 18. The status of power source 18 may be used for determination of the power that is being supplied to the IMD by the power source 18. For example, in examples where power source 18 includes a battery, IMD 210 may include components for determining (e.g., measuring, estimating, receiving, etc.) information related to a battery status, battery level, and / or other battery information (e.g., an amount of current drain from the battery, an amount of charge remaining in the battery, a power being supplied by the battery etc.). Components of IMD 210 for determining information related to the battery status include coulomb counter 35, switch 33, timer 41, and state control circuitry 31. Coulomb counter 35, switch 33, timer 41, and state control circuitry 31 may be used alone and / or in connection with other components of IMD 210, including processing circuitry 30.

[0074] In some examples, IMD 210 is configured to transition between different operational states. For example, processing circuitry 30 and / or state control circuitry 31 are configured to transition IMD 210 between different operational states where differentAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 components of IMD 210 are powered and operational. In a first device state (e.g., a therapy state or operational state) and / or during a first period of time, IMD 210 may be configured to deliver electrical stimulation therapy. Specifically, in the first device state, IMD 210 may be actually delivering therapy, or the components needed for IMD 210 to deliver therapy are receiving power but not actually delivering therapy (e.g., a device “standby” state). In a second device state, therapy is withheld or otherwise not scheduled, and IMD 210 may have one or more components disconnected or partially disconnected from power source 18 or otherwise in a state for consuming less power (e.g., a deep sleep state, a reduced power state, etc.). Processing circuitry 30 and / or state control circuitry 31 may also be configured to determine whether IMD 210 is in a given operational states. For example, processing circuitry 30 and / or state control circuitry 31 are configured to perform certain functions depending on whether IMD 210 is in a particular operational state (e.g., the first device state or the second devices state).

[0075] In some examples, IMD 210 uses one or more methods or combinations of components to determine the status of power source 18 of IMD 210 during different operational states. Using multiple methods of determining the status of power source 18 may optimize power loss from power source 18 while still maintaining a reliable determination of the status of power source 18.

[0076] In some examples, coulomb counter 35 is be configured to measure current drain from power source 18 (e.g., a battery) of IMD 210. Coulomb counter 35 may be configured to measure current drain during at least a first period of time in which the IMD is in a first device state (e.g., while the IMD is delivering electrical stimulation therapy via electrodes 17 or at least powered “on” and configured to delivery electrical stimulation therapy such as the “standby” state mentioned above). In some examples, coulomb counter 35 measures current drain directly from power source 18 (e.g., a battery) of IMD 210 during the first period of time. Coulomb counter 35 may output real-time current measurements that processing circuitry 30 uses to calculate a cumulative current used during a period of this may be part of or equal to the first period of time. In other examples, coulomb counter 35 may output an average current and / or cumulative current over a period of time to processing circuitry 30 for determining the current drain during the first period of time. Because coulomb counter 35 directly measures current drain from power source 18 (e.g., a battery), the measured current may be more accurate as comparedAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 to other methods of determining current drain (e.g., methods involving indirect measurement and / or estimation of current drain). Processing circuitry 30 may be configured to receive the measured current drain, or one or more values indicative of the measure current drain, from coulomb counter 35. In this way, processing circuitry 30 is configured to determine a recharge interval based on directly measuring battery current, alone or in combination with past or predicted current drain from power source 18. In one or more embodiments, the current drain measured by the coulomb counter 35 can be used to calculate one or more parameters of the power source 18, including, by non-limiting example, a current being supplied to the IMD 210.

[0077] As another example, IMD 210 may additionally or alternatively use more energy-efficient methods for estimating a battery status during a second period of time in which IMD 210 is in a second device state (e.g., a deep sleep state). In some examples, high-power circuitry or components of IMD 210 may be disconnected from power source during the second device state, which may include one or more of a deep sleep state or a reduced power state. For example, state control circuitry 31 may be configured to disconnect coulomb counter 35 from power source 18 (e.g., the battery) via switch 33 (e.g., a circuitry switch). State control circuitry 31 may, in some examples, disconnect coulomb counter 35 from power source 18 by opening switch 33. In this way, IMD 210 may be able to conserve power during the second device state because certain electrical components, including coulomb counter 35, are disconnected from power source 18. However, disconnecting coulomb counter 35 from power source 18 also disables coulomb counter 35 from directly measuring current drain during the second device state (e.g., a deep sleep state). In some examples, coulomb counter 35 may be connected in order to measure current drain from power source 18 during at least a portion of the second device state (e.g., a deep sleep state). Processing circuitry 30 may control state control circuity 31 to operate switch 33, or processing circuitry 30 may directly control switch 33 in other examples.

[0078] In some examples, one or more components of IMD 210 (e.g., processing circuitry 30, alone in combination with other components) may be configured to estimate current drain from power source 18 (e.g., battery) of IMD 210 for a second period of time during the second device state. As discussed above, this second period of time may include the coulomb counter 35 being disconnected and not available to measure theAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 current drain from power source 18. For example, where a coulomb counter 35 does not measure current drain from power source 18, one or more techniques may be used to estimate the current drain from power source 18. In some examples, processing circuitry 30, alone or in combination with other components, are configured to determine (e.g., calculate) an estimated current drain based on at least information indicative of a characterized current drain and information indicative of IMD 210 events. The information indicative of the characterized current drain, as well as information indicative of IMD 210 events, may enable IMD 210 to estimate (e.g., via a calculation) current drain from power source 18 (e.g., battery) during the second devices state (e.g., a deep sleep state). For example, the information indicative of the characterized current drain includes an amount of current drain per unit of time (e.g., amperes per hour), such that processing circuitry 30 determines current drain during the second devices state (e.g., a deep sleep state) based on the amount of time spent in the second device state and this expected, or estimated, current drain or other indication of battery usage. In some examples, processing circuitry 30 accesses information indicative of the characterized current drain from memory 32, programmer 104, server 112, or another suitable component. Processing circuitry 30 may be configured to receive information indicative of IMD 210 events from timer 41. To determine the estimated current drain during the second device state, processing circuitry 30 may be configured to access a lookup table, wherein the lookup table correlates at least the information indicative of IMD 210 events and the information indicative of the characterized current drain from power source 18.

[0079] In some examples, timer 41 is configured to provide information indicative of IMD 210 events, which may facilitate and / or enable determination of an estimated current drain during the second device state (e.g., a deep sleep state). Timer 41 may remain powered and operational during at least the second device state (e.g., a deep sleep state), but may also remain operation during the first device state (e.g., when IMD 210 is configured to deliver therapy). In some examples, timer 41 records the duration of time IMD 210 is in the second device state (e.g., a deep sleep state). Additionally, or alternatively, timer 41 records when IMD 210 transitions between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state) and vice versa. For example, timer 41 records one or more timestamps of at least one of IMD 210 entering or exiting the second device state. In this way, timer 411Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 may provide a processor, such as processing circuitry 30, with timestamps of when IMD 210 transitions between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state), which may enable processing circuitry 30 to determine (e.g., calculate) the duration of time spent in the first device state or the second device.

[0080] Although timer 41 provides information indicative of IMD 210 events in the example of FIG. 2, another suitable component may provide information indicative of IMD 210 events. For example, an external device (e.g., external computing device 108, programmer 104, and / or server 112 of FIG. 1) to IMD 210 may record information indicative of IMD 210 events. For example, external computing device 108, programmer 104, and / or server 112 records the duration of time IMD 210 is in the second device state (e.g., a deep sleep state). The external device (e.g., external computing device 108, programmer 104, and / or server 112 of FIG. 1) may be configured to send the information indicative of IMD 210 events to IMD 210.

[0081] In addition, or alternative, to the methods of determining a current drain from power source 18 and / or a status of power source 18 noted above, IMD 210, via processing circuitry 30, may be configured to measure a voltage of power source 18 (e.g., a battery) as part of determining the battery status or battery usages.

[0082] IMD 210, via processing circuitry 30, may be configured to determine a status of power source 18 (e.g., a battery status, in examples where power source 18 includes at least a battery). The determination of the status of power source 18 (e.g., a battery status) may be based on the measured current drain and the estimated current drain of the battery of the IMD for different respective periods of time in some examples. However, the status of power source 18 may be determined using only estimated current drain or only measured current drain in other examples. IMD 210, via processing circuitry 30, may be configured to generate, for output, information indicative of the status of power source 18 (e.g., a battery status, in examples where power source 18 includes at least a battery). Information indicative of the status of power source 18 (e.g., a battery status) may include an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, a date of charge depletion, an expected date of battery depletion, an expected date of battery recharge. In some examples, IMD 210, via processing circuitry 30, may be configured to generate, for output, information indicativeAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 of the status of power source 18 at predetermined events (e.g., battery percentage thresholds of remaining charge, such as 20 percent, 10 percent, etc.). The information is indicative of the status of power source 18 may be updated automatically on a periodic basis, after one or more events (e.g., a recharge session, the start or end of a therapy session, etc.), or upon interrogation of IMD 210 by an external device (e.g., programmer 104, external computing device 108, or server 112).

[0083] FIG. 3 is a block diagram of an example an external computing device of FIG.1. External charging device 208 in of FIG. 3 is an example of external computing device 108 described above in relation to FIG. 1. In some examples, external charging device 208 may be described as a hand-held device, in other examples, external charging device 208 may be a larger or a non-portable device. In addition, in other examples external charging device 208 may be included as part of an external programmer or include functionality of an external programmer. As shown in the example of FIG. 3, external charging device 208 includes a housing 24 connected to a charging head 226. Housing 24 encloses components such as a primary processing circuitry 50, memory 52, user interface 54, telemetry circuitry 56, control 62, one or more sets of indicator lights 64, audio output circuitry 70, haptic output circuitry 72 and power source 60. Charging head 226 may include charging circuitry 58, temperature sensor 59, and external primary coil 48. Charging head 226 and / or external primary coil 48 may be an example of external primary coil 26 as shown in FIG. 1. Housing 24 is electrically coupled to charging head 226 via a cable. Housing 24 may also include charging circuitry 68 and internal primary coil 228, which is an example of internal primary coil 28 described above in relation to FIG. 1.

[0084] In some examples, separate charging head 226 may facilitate positioning of external primary coil 48 over secondary coil 16 of IMD 10 (as shown in FIG. 1) or IMD 210 (as shown in FIG. 2). In some examples, charging circuitry 68 and / or internal primary coil 228 may be integrated within housing 24. In other examples, external charging device 208 may not include charging head 226. Memory 52 may store instructions that, when executed by primary processing circuitry 50, causes primary processing circuitry 50 and external charging device 208 to provide the functionality ascribed to external charging device 208 throughout this disclosure, and / or any equivalents thereof. External primary coil 48 and internal primary coil 228 may also be referred to as an antenna. In some examples, external charging device 208 may include secondary processing circuitry 40,Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 which may control telemetry circuitry 56, as well as perform other functions. Some other functions may include error checking of the operation of primary processing circuitry 50.

[0085] External charging device 208 may also include one or more temperature sensors, illustrated as temperature sensor 59 within charging head 226, similar to temperature sensor 39 of FIG. 2. As shown in FIG. 3, temperature sensor 59 may be disposed within charging head 226. In other examples, one or more temperature sensors of temperature sensor 59 may be disposed within housing 24. For example, charging head 226 may include one or more temperature sensors positioned and configured to sense the temperature of external primary coil 48 and / or a surface of the housing of charging head 226. In some examples, external charging device 208 may not include temperature sensor 59.

[0086] In general, external charging device 208 comprises any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the techniques ascribed to external charging device 208, and primary processing circuitry 50, user interface 54, telemetry circuitry 56, and charging circuitry 68 of external charging device 208, and / or any equivalents thereof. In various examples, external charging device 208 may include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. External charging device 208 also, in various examples, may include a memory 52, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, a hard disk, a CD-ROM, comprising executable instructions for causing the one or more processors to perform the actions attributed to them. Moreover, although primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and temperature sensor 59 are described as separate modules, in some examples, primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and / or temperature sensor 59 are functionally integrated. In some examples, primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and / or temperature sensor 59 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0087] Memory 52 may store instructions that, when executed by primary processing circuitry 50, cause primary processing circuitry 50 and external charging device 208 to provide the functionality ascribed to external charging device 208 throughout this disclosure, and / or any equivalents thereof. For example, memory 52 may includeAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 instructions that cause primary processing circuitry 50 to control the power supplied by the battery 210 in response to changes in a measured impedance, as communicated from IMD 210, or instructions for any other functionality. Memory 52 may include a record of selected power levels, measured impedances, sensed temperatures, determined temperatures, or any other data related to charging power source 18, described above in relation to FIG. 2. Memory 52 may store instructions that when executed by primary processing circuitry 50 may control the operation of indicator lights 64 as described above in relation to FIG. 1. Primary processing circuitry 50 may determine one or more operational states, e.g., of external charging device 208 and selectively control indicator lights 64 based on the operational state.

[0088] Primary processing circuitry 50 may, when requested, transmit any stored data in memory 52 to another computing device for review or further processing, such as to server 112 depicted in FIG. 1. Primary processing circuitry 50 may be configured to access memory, such as memory 32 of IMD 10 and / or memory 52 of external charging device 208, to retrieve information comprising instructions, formulas, and determined values for one or more constants.

[0089] User interface 54 may include buttons, such as control 62 or a keypad, lights, such as indicator lights 64, a speaker for voice commands, a display, such as a liquid crystal display (LCD), light-emitting diode (LED), or cathode ray tube (CRT). In some examples, the display may be a touch screen. Control 62 may be implemented as any type of component that may receive user input and provide an indication of the user input to primary processing circuitry 50. Control 62 may be a knob, switch, button, or another suitable structure. As discussed in this disclosure, primary processing circuitry 50 may present and receive information relating to the charging and / or the status of power source 18 (e.g., a battery) of IMD 210 via user interface 54. For example, user interface 54 may indicate when charging is occurring, quality of the alignment between internal primary coil 228 or external primary coil 48 and secondary coil 16 of IMD 210, the selected power level, current charge level of power source 18, duration of the current recharge session, anticipated remaining time of the charging session, sensed temperatures, or any other information. Primary processing circuitry 50 may receive some of the information displayed on user interface 54 from IMD 210 in some examples. In some examples, userAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 interface 54 may provide an indication to the user of the status of power source 18 of IMD 210.

[0090] User interface 54 may also receive user input via user interface 54. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. The input may change programmed settings, start, or stop therapy, request starting or stopping a recharge session, a desired level of charging, or one or more parameters related to a measured voltage, current, or power. In this manner, user interface 54 may allow the user to view information related to the operation of IMD 210. For example, control 62 may provide an input to primary processing circuitry 50 to cause primary processing circuitry 50 to start or stop delivery of wireless power to the power receiving device, e.g., IMD 10 or IMD 210 described above in relation to FIGS. 1 and 2. In at least one embodiment, the control 62 may provide an input to the primary processing circuitry 50 to cause primary processing circuitry 50 to adjust the one or more parameters related to a measured voltage, current, or power or to provide any of the processes described herein.

[0091] Charging circuitry 58 may include one or more circuits that generate an electrical signal, and an electrical current, within external primary coil 48. Charging circuitry 58 may generate an alternating current of specified amplitude and frequency in some examples. In other examples, charging circuitry 58 may generate a direct current. In any case, charging circuitry 58 may be capable of generating electrical signals, and subsequent magnetic fields, to transmit various levels of power to IMD 210. In this manner, charging circuitry 58 may be configured to charge power source 18 of IMD 210 with a selected power level.

[0092] Power source 60 may deliver operating power to the components of external charging device 208. Power source 60 may also deliver the operating power to drive external primary coil 48 during the charging process. Power source 60 may include a battery and a power generation circuit to produce the operating power. In some examples, a battery of power source 60 may be rechargeable to allow extended portable operation. In other examples, power source 60 may draw power from a wired voltage source such as a consumer or commercial power outlet.

[0093] Telemetry circuitry 56 supports wireless communication between IMD 210 and external charging device 208 under the control of primary processing circuitry 50.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 Telemetry circuitry 56 may also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. In some examples, telemetry circuitry 56 may be substantially similar to telemetry circuitry 36 of IMD 210 described herein, providing wireless communication via an RF or proximal inductive medium. In some examples, telemetry circuitry 56 includes an antenna 57, which may take on a variety of forms, such as an internal or external antenna. Although telemetry circuitry 56 and telemetry circuitry 36 may each include dedicated antennas for communications between these devices, telemetry circuitry 56 and telemetry circuitry 36 may instead, or additionally, be configured to utilize inductive coupling from internal primary coil 228 and / or external primary coil 48 to transfer data.

[0094] Examples of local wireless communication techniques that may be employed to facilitate communication between external charging device 208 and IMD 210 include radio frequency and / or inductive communication according to any of a variety of standard or proprietary telemetry protocols, or according to other telemetry protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.1 lx or Bluetooth specification sets. In this manner, other external devices may be capable of communicating with external charging device 208 without needing to establish a secure wireless connection.

[0095] In operation, primary processing circuitry 50, and / or secondary processing circuitry 40, may control one or more sets of indicator lights 64 to provide information to a user about communication, charging efficiency, therapy status of the IMD, or other applicable information. For example, primary processing circuitry 50 may determine whether communication circuitry, e.g., telemetry circuitry 56, has established a communication link with a power receiving device (e.g., IMD 10 or IMD 210 depicted in FIGS. 1 and 2). Primary processing circuitry 50 may also determine whether the power receiving device (e.g., IMD 10 or IMD 210) receives wireless power, e.g., via charging circuitry 68 and internal primary coil 228, or charging circuitry 58 and external primary coil 48.

[0096] Primary processing circuitry 50 may use any one or more system metrics to determine power transfer to IMD 210. In some examples, IMD 210 may send a signal indicating an amount of current output by the recharge circuitry of IMD 210. In other examples, primary processing circuitry 50 may calculate other system metrics, such as alignment of internal primary coil 228 to secondary coil 16 of IMD 210 using any ofAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 several techniques, including heat calculations, temperature measurements, detection of metal, and / or other suitable determinations. Primary processing circuitry 50 may compare any of the calculated power transfer, power efficiency, alignment, IMD 210 current, etc. to a threshold stored at memory 52. When above the threshold, primary processing circuitry 50 may cause indicator lights 64 to output a signal.

[0097] In some examples, primary processing circuitry 50 of external charging device 208 may be configured to determine the operational states of IMD 210. In some examples, primary processing circuitry 50 of external charging device 208 is configured to determine whether IMD 210 is in the first device state (e.g., when IMD 210 is configured to deliver therapy) and / or the second device state (e.g., a deep sleep state). Primary processing circuitry 50 of external charging device 208 may determine the operational state of IMD 210 instead of or in addition to processing circuitry 30 of IMD 210 as described above. Further, primary processing circuitry 50 of external charging device 208 may be configured to perform any of the functions related to determining a status of power source 18 of IMD 210, as well as additionally or alternatively determining a status of power source 60 of external charging device 208.

[0098] In some examples, primary processing circuitry 50 may control haptic output circuitry 72 to provide a tactile sensation above the patient’s perception level. For example, haptic output circuitry may vibrate or provide some similar tactile sensation. In some examples, primary processing circuitry 50 may control haptic output circuitry 72 to vibrate at a constant level for a specified duration, may output a pattern of vibration, or some similar haptic feedback for the patient. In some examples, the haptic feedback may indicate poor coupling, and the haptic feedback may fade as the coupling improves, e.g., the power receiving device is receiving wireless power above the first threshold. In this manner, the patient may receive feedback without the need to view user interface 54 of external charging device 208, or the user interface of some other device, e.g., a smart phone, tablet and so on. As discussed above, primary processing circuitry 50 may be configured to provide similar notifications or outputs related to the determination of the status of power source 18 of IMD 210. For example, primary processing circuitry 50 may control haptic output circuitry 72 to vibrate in a specific pattern to indicate to and / or alert the patient of the status of power source 18 of IMD 210.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0099] FIG. 4 is a block diagram of an example programmer 204 of FIG. 1.Programmer 204 may be a device for inputting information relating to a patient, receiving information from IMD 210, and updating IMD 210. In some examples, such as where programmer 204 is a patient programmer, programmer 204 can be a wearable communication device, with a therapy request input integrated into a key fob or a wristwatch, handheld computing device, smart phone, computer workstation, or networked computing device. Practically, programmer 204 can be a bring-your-own device provided by the patient, or provided by the healthcare provider in connection with the implantable device.

[0100] In some examples, such as where programmer 204 is physician / clinician programmer, programmer 204 is a tablet computing device that is preloaded with a specific application to interface with IMD 210. The physician or clinician may interact with programmer 204 for programming IMD 210. As described in more detail, the physician or clinician may utilize examples of a workflow to program IMD 210, as well as view information about the usage of IMD 210.

[0101] Programmer 204 generally comprises a processing circuitry 82, a memory 84, a user interface 86, communications circuitry 88, and a power source 90. Processing circuitry 82 can be any programmable device that accepts digital data as input, is configured to process the input according to instructions or algorithms, and provides results as outputs. In an example, processing circuitry 82 can be a central processing unit (CPU) configured to carry out the instructions of a computer program. Processing circuitry 82 is therefore configured to perform at least basic arithmetical, logical, and input / output operations. In one or more examples, processing circuitry 82 corresponds to individual hardware units, such as microprocessors, ASICs, DSPs, FPGAs, or other hardware units. In other examples, processing circuitry 82 can correspond to multiple individual hardware units, such as microprocessors, ASICs, DSPs, FPGAs, or other hardware units.

[0102] Memory 84 can comprise volatile or non-volatile memory as required by processing circuitry 82 to not only provide space to execute the instructions or algorithms, but to provide the space to store the instructions themselves. In one or more examples, volatile memory can include random access memory (RAM), dynamic random-access memory (DRAM), or static random access memory (SRAM), for example. In one or more examples, non-volatile memory can include read-only memory, flash memory,Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 ferroelectric RAM, hard disk, floppy disk, magnetic tape, or optical disc storage, for example. The foregoing lists in no way limit the type of memory that can be used.

[0103] Furthermore, memory 84 may include, in certain embodiments, instructions 302, system inputs 400, system outputs 500, one or more machine learning algorithms 304, and one or more lookup tables 306. Furthermore, in certain embodiments, the instructions 302, the system inputs 400, the system outputs 500, the one or more machine learning algorithms 304, and the one or more lookup tables 306 could be stored locally on the programmer 204, externally on the server 112, or both.

[0104] The instructions 302 can be stored the memory 84 to dictate how the processing circuitry 82 performs one or more of the methods or functionalities described herein. In certain examples, the instructions 302 are stored in a form of non-volatile memory (such as flash memory, ROM, or EEPROM) that the processing circuitry 82 can read from. In certain embodiments, the instructions 302 are stored as binary data that is specific to the processing circuitry 82 of the system 100.

[0105] The system inputs 400 and the system outputs 500 include data that can be stored in a programmer memory 84 or externally on the server 112 (which is accessible via the communications circuitry 88). The system inputs 400 and the system outputs 500 are illustrated and described in further detail with respect to FIGS. 5-6.

[0106] The one or more machine learning algorithms 304 can be stored in the programmer memory 84 or externally on the server 112 to execute one or more of the methods described herein. A machine learning algorithm 304 is a computational model that allows the system 100 to learn patterns or make predictions based on data (e.g., the system inputs 400), without being explicitly programmed for every task. The one or more machine learning algorithms 304 analyze data, recognize patterns, and improve its performance over time as it processes additional information. A primary goal of machine learning is to enable systems to generalize from data, allowing them to make accurate predictions or decisions when faced with new, unseen data.

[0107] In certain embodiment, the machine learning algorithm(s) 304 can include supervised learning or unsupervised learning. In supervised learning, the one or more machine learning algorithms 304 are trained on by providing a labeled dataset (e.g., a labeled dataset corresponding to one or more IMDs), meaning that the input data is paired with correct output labels (e.g., a labeled impedance measurement). The one or moreAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 machine learning algorithms 304 learn to map inputs to outputs (e.g., the system inputs 400 and the system outputs 500) by minimizing the difference between its predictions and the actual outcomes. Machine learning algorithm(s) 304 described herein may be used to generate a regression model, such as a non-linear regression model. A process by which the one or more machine learning algorithms 304 is trained using supervised learning is illustrated and described in further detail with respect to FIG. 13.

[0108] On the other hand, unsupervised learning involves training a model on data without predefined labels. The one or more machine learning algorithms 304 seek to identify hidden patterns or structures in the data, such as grouping similar data points into clusters (clustering) or reducing the dimensionality of complex datasets (dimensionality reduction). In certain embodiments, unsupervised learning is used to perform one or more of the methods discussed herein, including those illustrated and described in further detail with respect to FIG. 13.

[0109] In certain examples, the machine learning algorithms 304 may utilize data from a plurality of patients to determine new power level targets for the entire population of patients based on data over a certain time period. In certain embodiments, the new power level targets can be set according to a schedule at different times of day.

[0110] In certain examples, the one or more lookup tables 306 can be stored in the programmer memory 84 or externally on the server 112 to execute one or more of the methods described herein. In certain embodiments, the system 100 may use one or more lookup tables 306 to determine a measured impedance of surrounding tissue that interfaces with the IMD.[OHl] User interface 86 can include a button or keypad, lights, a speaker for voice commands, a knob able to turn, a display, such as a liquid crystal display (LCD), lightemitting diode (LED), or cathode ray tube (CRT). In some examples, the display may be a touch screen. Processing circuitry 82 can present and receive information relating to electrical stimulation and resulting therapeutic effects via user interface 86. For example, processing circuitry 82 can receive patient input via user interface 86. The input can be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. Processing circuitry 82 can also present information to the patient in the form of alerts related to delivery of the electrical stimulation to a patient or a caregiver via user interface 86. In some examples, user interface 86 may provide an indication to the user ofAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 the status of power source 18 of IMD 210. For example, user interface 86 may provide information indicative of the status of power source 18 (e.g., a battery status) including an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, an expected date (e.g., including month, day, and year) of battery depletion, or an expected date (e.g., including month, day, and year) of battery recharge. In certain embodiments, the user interface 86 can include buttons, a touch screen, or speakers similar to a cellular phone or other mobile device.

[0112] Communications circuity 88 is configured to interface with IMD 210 and optionally, server 112 (FIG. 1). Communications circuity 88 supports wireless communication between IMD 210 and, optionally, between server 112 and programmer 204 under the control of processing circuitry 82. Communications circuity 88 can also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. Communications circuity 88 can provide wireless communication via an RF or proximal inductive medium. In some examples, communications circuity 88 can include an antenna, which may take on a variety of forms, such as an internal or external antenna.

[0113] Examples of local wireless communication techniques that may be employed to facilitate communication between programmer 204 and another computing device include RF communication according to the 802.11 or Bluetooth specification sets, infrared communication, e.g., according to the Infrared Data Association (IrDA) standard, or other standard or proprietary telemetry protocols. In this manner, other external devices may be capable of communicating with programmer 204 without needing to establish a secure wireless connection.

[0114] Power source 90 delivers operating power to the components of programmer 204. Power source 90 can include a battery and a power generation circuit to produce the operating power. In some examples, the battery may be rechargeable by, for example, an exterior power source.

[0115] Accordingly, as described, programmer 204 allows the user (e.g., patient, caretaker, clinician, physician) to program a therapy schedule and adjust therapy parameters (e.g., amplitude, frequency, or pulse width). A therapy schedule may include a frequency and duration of stimulation therapy based on certain time intervals (e.g., times of the day, amount of days between therapy sessions, particular dates, or days of the weekAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 for therapy sessions, total duration, or number of therapy sessions, etc.). Programmer 204 can communicate with IMD 210 to update the functionality of IMD 210.

[0116] In some examples, programmer 204 is configured to perform one or more of the functions related to determining a status of power source 18 (e.g., a battery status) of IMD 210, as described above. For example, programmer 204, via processing circuitry 82, may be configured to estimate of the status of power source 18 for one or more periods of time or one or more devices states of IMD 210. In some examples, programmer 204 is configured to track or estimate the status of power source 18 (e.g., a battery status) even when not connected to IMD 210. In some embodiments, the programmer 204 can access one or more parameters

[0117] It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

[0118] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0119] Instructions 302 may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as usedAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0120] FIG. 5 is a block diagram illustrating example system inputs 400 that are received by the programmer of FIGS. 1 and 4.

[0121] The system inputs may include initial electrical parameters 410 and measured electrical parameters 420. In certain embodiments, the initial electrical parameters 410 include a first power measurement 412, an initial voltage 414, an initial charge 416, and an initial current 418.

[0122] In some embodiments, the first power measurement 412 can include a first measurement of power taken at the time the IMD 210 is implanted into a patient. The power may be measured, by non-limiting example, by measuring the total charge that flows out of the battery over time (to calculate the current) using the coulomb counter 35. The current can then be multiplied by the voltage of the battery to find the power consumption of the batter. In other embodiments, a voltage measuring device can be used when the voltage is not constant, and power can be found by multiplying a measured voltage by a measured current. Furthermore, in at least one embodiment, the first power measurement 412 can include the nominal voltage, rated voltage, or open-circuit voltage of the battery.

[0123] In certain embodiments, the initial voltage 414, initial charge 416, and initial current 418 can be measured at a time of implantation or prior to implantation (e.g., at a time of manufacturing). As described above, the initial voltage 414 can be measured using a voltage measuring device, the initial charge can be measured using a coulomb counter 35, and the initial current 418 can be measured by dividing the initial charge 416 by a unit of time. Furthermore, in at least one embodiment, an initial impedance of the tissue surrounding the IMD can be measured at a time of implant.

[0124] In at least some embodiments, the measured electrical parameters 420 include a measured voltage 422, a measured charge 424, a measured current 426, a measured impedance 428, and a second power measurement 430. In at least one embodiment, the measured electrical parameters 420 are all measured after a time at which the IMD is implanted into a patient. The measured voltage 422, a measured charge 424, and measured current 426 can each be measured using a voltage measuring device or coulomb counterAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 35 as illustrated and described above. The measured impedance 428 can be calculated using Ohm’s Law by dividing the measured voltage 422 by the measured current 426. Furthermore, in at least one embodiment, the second power measurement 430 can be calculated by using the formula power equals the measured voltage multiplied by the measured current having a phase angle equal to the cosine of theta (P=V4-cos(9)). The phase angle can be derived from the impedance as the cosine of theta is equal to the resistive part of the impedance divided by the magnitude of the total impedance (cos(9)=R / |Z|). This gives the real power (active power) in the circuit.

[0125] FIG. 6 is a block diagram illustrating example system outputs 500 generated by the programmer of FIGS. 1 and 5, in accordance with one or more embodiments of the present disclosure.

[0126] In certain embodiments, the system outputs 500 can include an adjusted current 502, an adjusted voltage 504, an adjusted power 506, and one or more user interface outputs 508.

[0127] As will be illustrated and described in further detail with respect to FIGS. 18-19, methods described herein can include utilizing one or more of the system inputs 400 illustrated and described above with respect to FIG. 4 to adjust the maintain a constant power draw of the IMD. In certain embodiments, the current, voltage, and power can be adjusted in response to a comparison between the first power measurement 412 and the second power measurement 430. In at least one embodiment, at least one of the measured voltage 422 and the measured current 426 can be adjusted when a difference between the first power measurement 412 and the second power measurement 430 is not within an acceptable range. In some embodiments, the acceptable range is at least ten percent of the first power measurement. In other embodiments, the acceptable range can be less than ten percent of the first power measurement, between ten and twenty-five percent of the first power measurement, or greater than twenty-five percent of the first power measurement. In at least one embodiment, one or more of the measured voltage, and measured current 426 can be adjusted (z.e., to generate an adjusted current 502 or an adjusted voltage 504) to also adjust the power (z.e., generate an adjusted power 506) to maintain a constant power draw over time as the impedance changes during wound healing processes.

[0128] Furthermore, in certain embodiments, the user interface outputs 508 can include one or more of the system inputs 400 and the system outputs shown in text orAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 illustrations. This output may be shown on a user interface, such as one on the external charging device 208 (e.g., user interface 54) or the user interface of the programmer 204 (e.g., user interface 86).

[0129] FIG. 7 is a scatter plot diagram 600 illustrating a stack setting 602 (z.e., how many capacitors are required to support a given voltage as stimulation increases) increasing as current amplitude 604, 614 and total impedance 606, 616 increases, in accordance with one or more embodiments of the present disclosure. A standard deviation plot 610 is also shown illustrating how much the number of capacitors required to support the given voltage fluctuates as the stimulation amplitude increases. The standard deviation plot 610 is important because it reflects the stability or variability of the system, helping to assess how consistent the capacitor requirements are under different stimulation conditions.

[0130] FIG. 8 is scatter plot diagram 700 illustrating an increase in the average current 702 that drains from a battery as the total impedance 706, 716 and current amplitude 704, 714 increases, in accordance with one or more embodiments of the present disclosure. Similar to FIG. 7 above, a standard deviation plot 710 is also shown illustrating how the average current required to support the given voltage fluctuates as the stimulation amplitude increases.

[0131] FIG. 9 is a three-dimensional scatter plot diagram 800 illustrating a relationship between the average current 802, the current amplitude 804, and the total impedance 806, in accordance with one or more embodiments of the present disclosure. As shown in the scatter plot diagram 800 by non-limiting example, the average current 802 may increase as the current amplitude 804 increases and the average current 802 may remain constant or may increase slightly as the total impedance 806 increases. Further, in at least one embodiment, the current amplitude 804 generally decreases as the total impedance 806 increases.

[0132] FIG. 10 is line plot diagram 900 illustrating changes in impedance 902 over time after implanting an IMD 904, in accordance with one or more embodiments of the present disclosure. As shown in the scatter plot diagram 900 by non-limiting example, a trendline 904 of the impedance 902 illustrates a sharp decrease in the impedance 902 in the first month after implantation and a gradual increase in impedance 902 thereafter. In some examples, this may occur because, during an initial phase of wound healing, theAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 body experiences inflammatory and granulation tissue formation. During this time, blood flow to the area increases, and the tissue around the implant becomes more vascularized (more blood vessels form), which can decrease the impedance. Further, fluid accumulation and cellular activity around the implant site may make the surrounding tissue more conductive, leading to a sharp decrease in impedance as the tissue becomes less resistive and more conductive in this early healing phase. In at least some embodiments, the impedance may slightly increase over time as the tissue begins to mature and form a more organized structure, and scar tissue might form around the implant. This fibrosis or scar tissue may increase the impedance because scar tissue tends to be less conductive than the early healing tissue. Further, as healing progresses, the tissue may become more compact and less vascularized, resulting in a slight increase in impedance over time.

[0133] FIG. 11 is a line plot diagram 1000 illustrating changes in impedance 1002 overtime 1004, 1014 including a variability gauge 1010 (e.g., a standard deviation plot diagram showing a standard deviation 1012), in accordance with one or more embodiments of the present disclosure. As shown in FIG. 11 by non-limiting example, the impedance sharply decreased during the first month with a high degree of variability, but then increased slightly thereafter with a lower degree of variability.

[0134] FIG. 12 includes data from a plurality of patients illustrating changes in impedance over time after implanting an IMD, in accordance with one or more embodiments of the present disclosure. The plurality of patients generally exhibited the same trends as illustrated and described above with respect to FIGS. 10-11, including a reduction in impedance over the first 2-3 months and a slight increase in impedance thereafter until twelve months after implantation.

[0135] FIG. 13 includes data 1200 from a plurality of patients illustrating changes in the current amplitude 1202 over time 1204 for a plurality of patients after IMD implantation, in accordance with one or more embodiments of the present disclosure. In certain examples, patients experiences an increase in current amplitude during the first three months after implantation and then generally remained constant thereafter.

[0136] FIG. 14 is a line plot diagram 1400 of stimulation power 1402 over time 1404 for a plurality of patients after IMD implantation, in accordance with one or more embodiments of the present disclosure. As shown in FIG. 15 by non-limiting example, aAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 trendline 1406 illustrates that the stimulation power 1402 remained relatively constant during the twelve months after implantation. .

[0137] FIG. 15 is a scatter plot diagram 1500 illustrating changes in stimulation power 1502 over time 1504, 1514 including a variability gauge (e.g., a standard deviation plot diagram 1510), in accordance with one or more embodiments of the present disclosure. As shown in FIG. 16 by non-limiting example, the stimulation power 1502 generally remained constant during the twelve months after implantation with a higher degree of variability immediately after implantation.

[0138] FIG. 16 is a method flow diagram of a method 1700 for supplying a constant power to a therapy delivery target, in accordance with one or more embodiments of the present disclosure.

[0139] The method 1700 includes a step 1702 of receiving information. In certain embodiments, the information relates to a therapy program of an implantable medical device comprising a first power measurement supplied to a therapy delivery target at an initial time (e.g., a time at which the IMD was manufactured or a time an initial time at which the IMD is implanted).

[0140] The method 1700 includes a step 1704 of measuring a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time. This step 1704 is illustrated and described in further detail with respect to FIGS. 5-6.

[0141] The method 1700 includes a step 1706 of determining a measured impedance. A process for determining a measured impedance is illustrated and described in further detail with respect to FIGS. 5-6.

[0142] The method 1700 includes a step 1708 of determining a second power measurement. A process for determining a second power measurement is illustrated and described in further detail with respect to FIGS. 5-6.

[0143] The method 1700 includes a step 1710 of comparing the first power measurement to the second power measurement and determining whether a difference between the first power measurement and the second power measurement is within an acceptable range. If the difference between the first power measurement and the second power measurement is within an acceptable range, then the method 1700 can be repeated by proceeding to step 1704. If the difference between the first power measurement and the second power measurement is not within an acceptable range, then one or moreAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 parameters (e.g., the measured voltage, the measured current, a supplied voltage, or a supplied current) can be adjusted at a subsequent time after IMD implantation to adjust the second power measurement such that the difference between the first power measurement and the second power measurement is within the acceptable range.

[0144] FIG. 17 is a method flow diagram of a method 1800 for training a machine learning algorithm to supply a constant power to a therapy delivery target, in accordance with one or more embodiments of the present disclosure. In certain embodiments, the machine learning algorithm can include supervised learning or unsupervised learning as illustrated and described above.

[0145] The method 1800 includes a step 1802 of providing a labeled dataset 1802. In certain embodiments, the labeled dataset includes information relating to one or more therapy programs. Furthermore, in at least one embodiment, the one or more therapy programs may include a first power measurement supplied to the therapy delivery target at an initial time, a voltage supplied by a power source at a subsequent time, a current supplied to the therapy delivery target at the subsequent time, and a labeled impedance at the therapy delivery target at the subsequent time.

[0146] The method 1800 includes a step 1804 of generating a regression model for determining a measured impedance at the therapy delivery target at the subsequent time, y non-limiting example, a regression model can be generated by analyzing and processing the labeled dataset, selecting a regression model, splitting the data into a training set and a testing set, and using training data to fit the regression model. In certain embodiments, the regression model is a non-linear regression model. In at least one embodiment, the regression model can include one or more of an exponential model, a logarithmic model, a power-law model, or a custom model.

[0147] The method 1800 includes a step 1806 of determining a second power measurement using the regression model. A process for determining a second power measurement is illustrated and described in further detail with respect to FIGS. 5-6.

[0148] The method 1800 includes a step 1808 of evaluating whether a performance of the machine learning algorithm is acceptable by comparing a first power measurement to a second power measurement. If the difference between the first power measurement and the second power measurement is not within an acceptable range, then the machine learning algorithm can be adjusted 1812 and step 1806 can be repeated. If the differenceAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 between the first power measurement and the second power measurement is within an acceptable range, then the machine learning algorithm 1810 can be locked for future use to analyze patient data.

[0149] The aspects of the invention described herein are provided by way of example and are not intended to be limiting to the disclosure in any manner. It should be understood that various modifications, substitutions, and alterations may be made to the embodiments described without departing from the scope and spirit of the invention. The features and elements described herein may be combined in various ways, and additional features may be incorporated as would be understood by those skilled in the art. The disclosure is intended to encompass all such variations, combinations, and equivalents that fall within the scope of the appended claims.

[0150] According to a first aspect, the present disclosure includes a system including: processing circuitry configured to: receive information relating to a therapy program of an implantable medical device including a first power measurement supplied to a therapy delivery target at an initial time; measure a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time; determine, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time; determine, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; compare the first power measurement to the second power measurement; and adjust at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0151] In a second aspect of the system of the first aspect or any other aspect, wherein the initial time is at a time of implanting the implantable medical device.

[0152] In a third aspect of the system of the first aspect or any other aspect, wherein the subsequent time comprises one or more of two weeks, four weeks, two months, three months, six months, or twelve months after the implantable medical device is implanted into a patient.

[0153] In a fourth aspect of the system of the first aspect or any other aspect, wherein the subsequent time is greater than twelve months after the implantable medical device is implanted into a patient.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0154] In a fifth aspect of the system of the first aspect or any other aspect, wherein the processing circuitry is further configured to determine the second power measurement supplied to the therapy delivery target at a plurality of subsequent times.

[0155] In a sixth aspect of the system of the first aspect or any other aspect, wherein the processing circuitry is further configured to continuously determine the second power measurement supplied to the therapy delivery target.

[0156] In a seventh aspect of the system of the first aspect or any other aspect, wherein the processing circuitry is further configured to determine the first power measurement by calculating a nominal power at the time of implanting the implantable medical device.

[0157] In an eighth aspect of the system of the first aspect or any other aspect, wherein the processing circuitry is further configured to determine the measured impedance at a power level below a perception level of a patient.

[0158] In a ninth aspect of the system of the first aspect or any other aspect, wherein the acceptable range is at least ten percent of the first power measurement.

[0159] In a tenth aspect of the system of the first aspect or any other aspect, wherein the measured impedance is determined using a non-linear regression model.

[0160] According to an eleventh aspect of the present disclosure, a method for supplying a constant power to a therapy delivery target including: receiving information relating to a therapy program of an implantable medical device comprising a first power measurement supplied to the therapy delivery target at an initial time: measuring a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time; determining, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time; determining, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; comparing the first power measurement to the second power measurement; and adjusting at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0161] In a twelfth aspect of the system of the eleventh aspect or any other aspect, further comprising determining the second power measurement supplied to the therapy delivery target at a plurality of subsequent times.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0162] In a thirteenth aspect of the system of the eleventh aspect or any other aspect, further comprising continuously determining the second power measurement supplied to the therapy delivery target.

[0163] In a fourteenth aspect of the system of the eleventh aspect or any other aspect, wherein the initial time is a time at which the implantable medical device is implanted into a patient.

[0164] In a fifteenth aspect of the system of the eleventh aspect or any other aspect, wherein the subsequent time is one or more of two weeks, four weeks, two months, three months, six months, or twelve months after the implantable medical device is implanted into a patient.

[0165] In a sixteenth aspect of the system of the eleventh aspect or any other aspect, wherein the subsequent time is greater than twelve months after the implantable medical device is implanted into a patient.

[0166] In a seventeenth aspect of the system of the eleventh aspect or any other aspect, wherein the measured impedance is determined using a non-linear regression model.

[0167] According to an eighteenth aspect of the present disclosure, a method for training a machine learning algorithm to supply a constant power to a therapy delivery target including providing a labeled dataset comprising information relating to one or more therapy programs, the one or more therapy programs including: a first power measurement supplied to the therapy delivery target at an initial time; a voltage supplied by a power source at a subsequent time; a current supplied to the therapy delivery target at the subsequent time; and a labeled impedance at the therapy delivery target at the subsequent time; generating a non-linear regression model for determining a measured impedance at the therapy delivery target at the subsequent time; determining, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time; evaluating the machine learning algorithm’s performance by comparing the first power measurement to the second power measurement; and adjusting the non-linear regression model when a difference between the first power measurement and the second power measurement is not within an acceptable range.

[0168] In a nineteenth aspect of the system of the eighteenth aspect or any other aspect, wherein the regression model is a non-linear regression model.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001

[0169] In a twentieth aspect of the system of the eighteenth aspect or any other aspect, wherein the non-linear regression model comprises at least one of an exponential model, a logarithmic model, a power-law model, or a custom model.

[0170] In a twenty-first aspect of the system of the first aspect or any other aspect, wherein the acceptable range is at least ten percent of the first power measurement.

[0171] In a twenty-second aspect of the system of the first aspect or any other aspect, wherein the acceptable range is between ten to twenty-five percent of the first power measurement.

[0172] In a twenty -third aspect of the system of the first aspect or any other aspect, wherein the acceptable range is approximately twenty-five percent of the first power measurement.

[0173] In a twenty-fourth aspect of the system of the first aspect or any other aspect, wherein the acceptable range is less than ten percent of the first power measurement.

[0174] In a twenty-fifth aspect of the system of the first aspect or any other aspect, wherein a user (e.g., a clinician or a patient) selects the first power measurement and the system maintains the first power measurement over a period of time.

[0175] In a twenty-sixth aspect of the system of the first aspect or any other aspect, wherein the system includes a remote programming agent that is configured to set a power level of the system.

Claims

1. Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 WHAT IS CLAIMED IS:

1. A system comprising:processing circuitry configured to:receive information relating to a therapy program of an implantable medical device comprising a first power measurement supplied to a therapy delivery target at an initial time;measure a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time;determine, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time;determine, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time;compare the first power measurement to the second power measurement; and adjust at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a difference between the first power measurement and the second power measurement is not within an acceptable range.

2. The system of claim 1, wherein the initial time is at a time of implanting the implantable medical device.

3. The system according to any of claims 1-2, wherein the subsequent time comprises one or more of two weeks, four weeks, two months, three months, six months, or twelve months after the implantable medical device is implanted into a patient.

4. The system according to any of claims 1-3, wherein the subsequent time is greater than twelve months after the implantable medical device is implanted into a patient.

5. The system according to any of claims 1-4, wherein the processing circuitry is further configured to determine the second power measurement supplied to the therapy delivery target at a plurality of subsequent times.Attorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 6. The system according to any of claims 1-5, wherein the processing circuitry is further configured to continuously determine the second power measurement supplied to the therapy delivery target.

7. The system according to any of claims 1-6, wherein the processing circuitry is further configured to determine the first power measurement by calculating a nominal power at the time of implanting the implantable medical device.

8. The system according to any of claims 1-7, wherein the processing circuitry is further configured to determine the measured impedance at a power level below a perception level of a patient.

9. The system according to any of claims 1-8, wherein the acceptable range is at least ten percent of the first power measurement.

10. The system according to any of claims 1-9, wherein the measured impedance is determined using a non-linear regression model.

11. A method for supplying a constant power to a therapy delivery target comprising:receiving information relating to a therapy program of an implantable medical device comprising a first power measurement supplied to the therapy delivery target at an initial time;measuring a voltage supplied by a power source and a current supplied to the therapy delivery target at a subsequent time;determining, based on the measured voltage and the measured current, a measured impedance at the therapy delivery target at the subsequent time;determining, based on the measured impedance, a second power measurement supplied to the therapy delivery target at the subsequent time;comparing the first power measurement to the second power measurement; and adjusting at least one of the measured voltage and the measured current supplied to the therapy delivery target at the subsequent time when a differenceAttorney Docket No.: 569448-969 (521WO01)Applicant Ref.: A0013260W001 between the first power measurement and the second power measurement is not within an acceptable range.

12. The method of claim 11, further comprising determining the second power measurement supplied to the therapy delivery target at a plurality of subsequent times.

13. The method according to any of claims 11-12, further comprising continuously determining the second power measurement supplied to the therapy delivery target.

14. The method according to any of claims 11-13, wherein the initial time is a time at which the implantable medical device is implanted into a patient.

15. The method according to any of claims 11-14, wherein the subsequent time is one or more of two weeks, four weeks, two months, three months, six months, or twelve months after the implantable medical device is implanted into a patient.

Images